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MG MGF Technical - Lowering knuckle dismentled itself

Hi, I think I had this problem for a while, just couldn't regenerate it that often.

Front Lowering knuckle on the passenger's side has gone busted, and making a horrible thunk noise when I go in a deep driveway where it requires a suspension travel. I can generate the noise by putting the jack up on the front and down, and the same noise is heard. After taking the wheel off, found that the lowering knuckle was out in play. Rubber ring was detached and cut in half. The white plastic part broken.

I only had it for 2 months. I emailed Mike Satur, hope he is working at the moment. Don't like driving it around but have no choice...

Do you know if Mike has warranty on his products? :-D

And has anyone had the same problem.
Hanah Kim

Dismentled Hanah? Is this a new fangled psychiatric term I've not come across??? ;o) ;o) ;o)

How are you sure that the problem is with the knuckle mate? I know that SF has had a similar problem with a set of lowering knuckles (also MS), but that needn't be the same cause in your case. The only way of knowing is to remove the knuckles for inspection - and if you do this ofcourse, you'll need to have replacements to hand if the knuckle has disintegrated. :o(
Rob Bell

When I had my suspenion modifieed by Techspeed they found that one of the lowering knuckles had come apart (one car for about 11 months) so was re made and as far as I know has not been a problem since.

Hanah

Maybe you can repair it with bits from your original knuckles?

Tom
Tom Randell

Hi guys, good to read your replies. My favourite people! (and SF / Dieter / Ted / Roger / Carl / Mike... and so and so!!)

Rob, that's exactly right. I am trying to negotiate with Mike, if he can send me a spare one, and if not required, I will send it back, and if required, I will pay for it. I don't have a spare car, and the garage is an hour away. And have exams in 20 days. Cannot waste too much time / or be without the car for too long.


Tom,

Mike suggested same idea. I just hope the middle pin is not damaged. That's the only different part so he tells me! :-) I still have the originals, but that depends on which parts are still ok. That's a gamble till I get to the garage again.


One query is that my mechanic's hydragas pump is in 'bars' and my car is on 38 bars! That's about 550psi. (i know 400) And my car height is still on 310mm! I think there is something wrong with the pressure gauge on the pump. Surely the car couldn't have gone down that much...with the kits. Any ideas what's causing this?
Hanah Kim

The problem i had was the plastic surround and rubber 'boot' had perished, this had led to the pin and bearing rusting, until the bearing became fused to the lower wishbone.

Mike's (and everyone else') lowering knuckles are cut down/re-machined standard ones, so this problem will affect them too.

SF
SF

Had mine from Mike S as well,no probs yet:-) will keep fingers crossed especially after throwing her around Silverstone circuit this year,glad you've found prob at long last Hanah, Dave T6 DCM
DC MORRIS

Hi all,

indeed the damage to the plastic insert can happen to all ball joints. Lower pin or not is anyway.

All that stuff is from only one original manufacturer, I think in the UK or in Belgium.

I have about eight or more of such plastic thingies at home. So if anyone needs one, let me know.

Dieter
Dieter K.

Thanks for the replies guys.

So a few of you guys also had problems as well...

Dieter, when you said

>>indeed the damage to the plastic insert can happen to all ball joints. Lower pin or not is anyway.

Do you mean that only the plastic part is likely to get damaged? And others are unlikely to?
At the moment only thing I am worried about is the middle pin.

If so I guess I will ask my mechanic to use the old MG ones to fit on to the new one? And everything would be ok?

Hanah Kim

My hydragas system requires too much pressure to get the ride height I am on.

And maybe thinking about going back to the normal original knuckles.

at 550psi, something is not right, and me and my mechanic are trying to figure out what is wrong.

Or just have to go back to the original knuckles.

And I wasted 300 pounds just for this... damn it! I will check the other side of the car as well and see if that is damaged.

Not feeling too happy about this.

Why am I not getting the right 330mm ride height after installing the lowering knuckles with right pressure? More likely at 290mm. I am on 310mm with 550psi! (38bar)

Hanah Kim

Also was there anything special I needed / mechanic needed to do when replacing the knuckles? It's just a straight swap right?

Thanks
Hanah Kim

Hanah

What sort of hydrogas pump is being used as there has been problems if the wrong sort is used. The best pumps are the vacum variety which removes all the air before putting in the fluid.
The other problem could be the pressure gauge being wrong as normally 400 psi is enough and is about the std pressure with both std and lowering knuckles.

What ride height did you have before the lowering knuckles and at what pressure?

Tom
Tom Randell

Hi Tom,

Thanks for the reply. I hope your electric problem is all solved!

I don't know what sort of pump it is, but my mechanic says he is putting about 28 bars (which equates to be 407psi) on other cars that he put the thing into. So another 10 bar is very excessive. When the car was on 28bars, the car height was 290mm. Adding another 10 bar of pressure didn't lift up the car much more and is at 310mm. The height is liveable with, but don't want to go much lower. Funny thing is when I was on 290mm, I felt the car was too much like floating, and when the pressure was increased the suspension was firmer giving me a better ride.

The ride height I was on was about 335mm without knuckles and probably was on a very low pressure.

Hanah Kim

I am going to see the mechanic at 6:30AM tomorrow as he will come in early to sort out the problems. He is keen on going back to normal knuckles again.

:-(

First attempt will be checking the right side (driver's) and see if the knuckle is ok there.

If it's ok, will proceed to get the left one fixed, hopefully it's fixable using the old parts.

But main concern is the high pressure in the hydragas unit. Maybe lower it, but then I will be doing 300mm height.
Hanah Kim

Regarding the pressure, I'd be doubting the accuracy of the hydragas pump guage (these can become damaged). Set your ride height correctly, and don't be too concerned about the absolute value. If the ride feels normal, then I'd be reassured that all was well.

If the pressure reading continues to bother you, get a 'second opinion' from another pump.

Knuckles are usually just a direct swap. Just a bit of a fiddly job, but one that won't bother any competant mechanic.
Rob Bell

Thanks Rob.

What does spacer washer look like?

Mike S, told me that this might be missing. (well maybe forgot to be swapped over).

I will check today. in an hour time.

I might be able to access internet from my mechanic's garage.

Hanah Kim

>At the moment only thing I am worried about is the middle pin.

I think nothink can break it. Though if the lower plate with cone is missing... but that seams impossible.

Anyway.
Two problem options from the MoD.

First option is non precise gauge.
I use as a simple acetylen bottle instrument as recommendet by Carl the other year.
Low danger of beaking anything, cause it's really made for all day use.

Second, .... I'm afraid....
I think one of the nitrogen upper spheres may have gone to no pressure.
In that case I think all the fluid while pumping will 'disappear to the upper hydragas unit can.
Not sure about the reaction !!! To be approved by someone else.

The missing washer case an influence on height is a depends on.... how high have they been before loss.

The lever relation is 1 : 4 at that pint.
Means if you add 1mm washer the the height will go up by 4mm.
I've seen myself only a few different of that alloy washers until now. The bigges was I think 3 or 4 mm.
So the height change will be indeed up to 15mm !!!

The washer inner diameter MUST be 17mm. Material is anyway. They used aluminum or steel. Would recommend steel made washers. Outer dia is nearly anyway. Anything larger then 22mm will do.

15mm height is about 8 to 10 Bar from my own experiance. The four washers all around may be different height, just as required to keep the car balanced related to equal pressure.

Another check theory regarding broken upper Hydragas sphere while pumping up from new after the system was empty and as well for the rough gauge precision is as follows:

There is a kind of 'rest point' while fluid gets pumped in. At about 20 Bar.
At that location the pressure doesn't increase while pumping. Gauge arrow remains there for 10 or what pump strokes and does nothing. That point is I think, when the fluid volume overcomes the reverse pressure of the inner valves and flows into the upper sphere.

Some links to the mad site
http://www.mgfcar.de/pump/guidopump.html
Forgive my english skills. That was 3 years ago, and it ain't got very much better.

http://www.mgfcar.de/lowering/index.htm
*Knuckle Works*

Hope this makes sense.

Rgds
Dieter
htp://www.mgfcar.de
Dieter K.

Err, makes low sense.
Some letters missing in any way ;)

should mean:
----------------
The missing washer case and it's influence on the height is a depends on *how high have they been before the got lost*.

The lever relation betweeen pin way to wheel centre way is 1 : 4 at the upper arm.
--------------------------------

better now ?
;)
Dieter K.

Oh yes. It's really to late to write AND think.
I'm sorry, checked the drawing and found:

The washer inner diameter MUST be 16mm. (not 17mm)

Now the next one please.
Dieter K.

Thanks Dieter for your detailed information like usual!

I took some photos today and have sent you the copies of them.

And the suspension is fixed for now: This is what I wrote to Mike Satur.


<<<Thanks so much for the reply Mike,

I went to visit my mechanic at 6:50am, and he was there waiting for me.

The right side was ok. So tackled the left side.

The problem was that there was no silver metal within the white plastic!! The mechanic showed me the marks on the middle pin, and yes, the silve metal part was there before, and there is a trace of it, but somehow that got dislodged and must be somewhere on the ground in Auckland somwhere. Our guess is that the suspension travel was so excessive that it got out.

My pressure is finally on 400psi with a ride height that is highter than before. I am guess there was a problem with the hydragas pump. I took some photos of it and attached them on this email. I am guessing the reason why I was sitting on 290mm was that the hydragas has not been pumped up to 400psi, (even though that's what it said on the guage).

The problem is solved for now, (even fixed rattling door while th mechanic was working on the car), but he is still worried what has caused it. What I think is it happened in a very early stage, when the car was too low.>>

Cheers all guys. I just hope this doesn't happen again..

Thanks.

Hanah Kim

Good to hear about a happy ending Hanah :o)
Rob Bell

Thanks Rob!
:0)

Hanah Kim

Got the pix.

MAte, a third thery is to the missing washer !

Looks like the pin worked out to damage the inner drill of the ally piston.
The shoulder where the pin rests on the piston is very small.
And the idiots (I'm sorry) at Dunlop used to 'lower' the piston drill by 45° to deap !!
I saw one where the depth was 2mm instead of required 'remove flash only'

Result could be that the pin slipped into tzhe drill hole and now clamps in the lower HG-piston. It now got pulled out from the control arm bearing and damaged the plastic part.

So initial failure cause is the missing washer and then the to deap 45° drill.

That's what I found from the two pictures.
The pump used is the standard old MGR pump. Nothing to complain at it.

The fix for the problem is:
- Replace plastic with any of your old knuckles.
- pull out the pin from the HG-piston
- use support washer with 2mm minimum height made from steel.

I'm 90 percent sure that I'm right. Anyone likes to bet ? :)
Hanahs pix upload to follow this night.
Please take a picture of the drill in the hydragas unit and another of the pin clamping in the hole if you find time.

HTH
Dieter
Dieter K.

BTW, I think I'll ask SF regarding his corroded knuckle joint whether the vital washer was missing.

Andy, are you out there ?
Do you recall about the existance of the alloy washer ?
Can it be possible that the coil spring inside the hydragas piston did not hold down the pin any longer and do you think this could be the true reason for the broken plastic holder ?

Dieter
Dieter K.

Dieter,

Thanks for your email and reply.

My mechanic tells me that he has placed the washer in the first place? He tells me he replaced only the knuckle and put everything else back in.

So the picture on the otherside has the spacer washers? (the part that wasn't damaged) I can't really tell. The car sits on the right ride height with right pressure. About 320mm ~ 330mm now. It's higher than before. (and ride is more comfortable)

When the pressure was checked before taking the hydragas out, it was sitting on 20bar (28bar=400psi), so it was way too low. But I remember that the pressure I put into the car last time was upto 38bar! (I saw it with my own eyes) Does this mean, that there was something wrong with the pump at the time...?

Or am I still missing the spacer washers?

The problematic photo was when taken before it was fixed. I haven't taken the photo after fixing it.

The white plastic part was not damaged. Nothing was damaged except for a thin rubber surrounding on the bottom. The small metal part that middle pin sits on has disappeared!

What my theory for this problem was that the pressure in the gas system was too low in the first place, thus allowing a huge travel in the suspension, and I do have to go through rather deep driveways, thus when doing so, the travel was excessive, letting the wheel free in the air, (as I go in diagonally) letting the metal part to pop out, and the middle pin was sitting on nothing ever since?

That's the best guess that I have so far..

What do you think?
Hanah Kim

Only in short. Picture from Hanah with the problem before fix is on the bottom left of that site.
http://www.mgfcar.de/defects/index.htm

Mate, I'm still on my theory that the missing washer and a sticking pin (rod) inside the piston has caused a 'lift up' of the whole knuckle.

Plastic part not damaged. So far so good.
But the missing lowest roll part is a clear indication that it was ...
1/ never in ?
or
2/ lost when the whole knuckle got pulled out while the car was bouncing up and down.

That roll surface part in the upper arm is more then 5mm, from what I recall !!

http://www.mgfcar.de/lowering/rod1.jpg
http://www.mgfcar.de/lowering/ tells more

Check the theoretical look of hydragas piston to rod at the bottom left of this picture
http://www.mgfcar.de/lowering/lowbolt_.jpg

and compare with the true look of the piston with the IMO dangerous 45° cone drill.
http://www.mgfcar.de/lowering/no_cone.jpg

Without washer I'm sure there may come up a problem at any time, special on bad NZ roads from yourself usual mentioned.

Anyway, everything seams fine from what I can see of your message.

The final question is:
Are the other rods mounted with washers ?

and at last my humble *MoD* question:

Who is the next with that sleeping trouble ;)
Ladies and Gentleman beware of lost and missing spacer washers after any works at your hydragas system.
I think a missing spring between rod and hydragas ally piston my cause the same poor result at any time. The spring looks useless but it isn't. It always should hold down the rod and rest of the knuckle inside the upper arm.

I wonder what SF says. Wrote a call by email to him.

Cheers
Dieter
Dieter K.

I tend to agry with Dieter, the damage was obviously caused by the whole knuckle being pulled up from its seat. This could have happenned because of the pin sticking in the piston, a bend or not properly fitted spring, too much grease in the piston, too low preassure and too many big potholes. It is probably a combination of all these factors.

I think the best thing to do is to check our knuckles regurarly.

Spyros
Spyros Papageorghiou

Will check it regularly Spyros. Good recommendation, same from my mechanic. My service is due in November, he wants to check it again then.

And thanks Dieter for your answer.
I am a little worried that the spacer washers could be missing on the other sides, but my mechanic assures me it's all there. By the way the height around the car seems all equal. (will measure it soon)

Hanah Kim

This thread was discussed between 08/10/2002 and 12/10/2002

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